Plunger and die devices for interlocking box walls



PLUNGER AND DIE DEVICES FOR INTERLOCKING BOX WALLS Filed Aug. 2, 1968 July 21, 1970 c. J. PIERCE, JR

l1 Sheets-Sheet l 'INVENTOR.

Chesfer d7 Pierce, 7/:

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* ATTORNEY July 21, 1970 c. J. PIERCE, JR 3,521,530

PLUNGER AND DIE DEVICES FOR INTERLOCKING BOX WALLS Filed Aug. 2,1968 l1 Sheets-Sheet 2 1Q =f= Q Q INVENTOR. Chesfer J: Pile/Ce, 7/.-

ATTORNEY y 1.970 c. J. PIERCE, JR 3,521,530

PLUNGER AND DIE DEVICES FOR INTERLOCKING BOX WALLS INVENTOR. 6/1esler .Z Pierce, Jr:

ATTORNEY Ju y 1970 c. J. PIERCE, JR I 3,5

PLUNGER ANDDIE DEVICES FOR INTERLOCKING BOXWALLS Filed-Aug. 2. 1968 11 Shets-Sheet 4 8 O I Q;

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INVENTOR. Cheszer I Pierce,J:

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- July 21, 1970 v c. J. PIERCE; JR I 3,521,530

PLUNGER AND DIE DEVICES FOR 'INTERLOCKING BOX WALLS Filed Aug. 2, 1968 11 Sheets-Sheet '5 II I H INVENTOR.

C/r'esfer J. Pierce, Jr.

7 4 Arromgy July 21, 1970 c. J. PIERCE, JR

PLUNGER AND DIE DEVICES FOR INTERLOCKING BOX WALLS i 2 Filed Aug. 2, 1968 11 Shee ts -Sheet 6' fit I: Riga 2O July 21, 1970' c. J. PIERCE, JR

NGER AND DIE ll Sheets-Sheet '7 Filed Aug. 2, 1968 v July 21, 1970 c. .LPIERcE, JIQ 3,521,530

PLUNGER AND DIE DEVICES FOR INTERLOCKING BOX WALLS Filed Aug. 2, 1968 11 sheets-shat s INVENTOR. Chester JT Pierce, Jr.

nomvsy July 21, I970 C.'J. PI ERCE, JR 3,521,530

' PLUNGER AND DIE DEVICES FOR INTERLOCKING BOX WALLS I Filed Aug. 2. 1968 ll Sheets-Sheet 9 a l ATTORNEY July 21, 1970 c. J. PIERCE, JR

I PLUNGER AND DIE DEVICES FOR INTERLOCKING BOX WALLS Filed Aug. 2, 1968 ll Sheets-Sheet 1O INVENTOR. Cheszer J Pierce, J}:

ATTORNEY July 21, 1970 c. .1.- PIERCE, JR 3,521,530

PLUNGER AND=DIE DEVICES FOR INTERLOCKING BOX WALLS 'Filecl Aug. 2, 1968 11 Sheets-Sheet 11 INVENTOR. Chesfer J: Pierce, Jr:

w I'ATTORNEY United States Patent Office 3,521,530 Patented July 21, 1970 3,521,530 PLUNGER AND DIE DEVICES FOR INTERLOCKING BOX WALLS Chester J. Pierce, Jr., Palo Alto, Calif., assignor to Kliklok Corporation, New York, N.Y., a corporation of Delaware Filed Aug. 2, 1968, Ser. No. 749,759 Int. Cl. B3lb 1/44 US. Cl. 93-5l 6 Claims ABSTRACT OF THE DISCLOSURE A plunger-and-die device is provided for converting a flat box blank into box form and interlocking the blank at the box corners in which the plunger comprises the customary projecting element on the plunger wall for opening an insertion slot in a wall panel for a corner lock flap and a movable finger which displaces a tab, tip or lug of the blank past an edge of an aperture to set a safety catch which keeps the flap lock engaged. The finger is retracted before the plunger reaches the end of its stroke, and the setting of the safety catch is assisted by a backup element opposing the finger motion. This element is a bar, plate or roller on the die or a flat blade on the plunger projecting slightly from a plunger wall and serves the double function of opening the insertion slot and acting as a back-up element.

The prior patent to Pagendarm 2,580,189 of Dec. 25, 1951 discloses a carton folding mechanism in which a plunger moves a flat carton blank or box blank through a forming die which is open at both top and bottom. The die folds the blank about the plunger, thus erecting the box walls with respect to the box bottom, folds corner lock flaps over certain wall panels and inserts them in slots in the latter.

The known device comprises elements protruding from the plunger sides or ends which bear against the blank as it is being folded about the plunger to open the insertion slots for the corner flaps. These elements are either buttons or blades fixedly mounted on the plunger so as to project slightly from the plunger surfaces, or they are projectible and retractable hooks under which a tip of the lock flap is first inserted and which are then retracted during the travel of the plunger through the die in order to pull an oversized lock flap tip to the inside of the box through a smaller aperture.

The known devices are not suitable for the style of corner locks in which the lock is set by displacing certain elements towards the outside of the box. This style of lock is disclosed in my copending application Ser. No. 749,647, filed Aug. 2, 1969, now Pat. No. 3,481,525 issued Dec. 2, 1969.

A blank folding and corner locking device comprising a plunger and a die through which the plunger is movable, in which the plunger comprises a bottom, sides and ends and in which the die comprises a side folder for folding a certain side panel of the blank against the plunger side, and in which the die comprises, further, opposite the plunger end, a corner slide for folding the lock fiap over the end panel while the end panel is being erected, and in which device the plunger further comprises at its end a protruding element adapted to engage the end panel adjacent an insertion slot in order to open the slot for insertion of the lock flap, and in which the device comprises a back-up element limiting deflection of the blank away from the plunger end, the protruding element being located between the corner slide and the said back-up element, is improved according to this invention by the provision of a movable finger on the plunger in a position to engage a lock tab or lug to force it outwardly towards the die, together with actuating means so timed, with respect to the plunger travel through the die, as to reach a position of maximum projection beyond the plunger end before the box edge of the blank passes beyond, and is disengaged from, the side folder, and to move into retracted position by the time the plunger reaches the end of its stroke through the die.

Suitably, the movable finger is mounted in a position substantially opposite the lateral edge of the corner slide and is projected after passing the slide.

The back-up element may be mounted on the die to engage the end panel adjacent the insertion slot to urge the end panel towards the plunger at a corner zone below the corner slide.

The backing-up function may also be performed by an element on the plunger. In that case the protruding plunger element assumes the shape of a blade directed towards the adjacent plunger corner, the length of the blade being sufiicient to permit the lock flap to pass under the blade into fully inserted position through the insertion slot, in which position the end of the blade terminates adjacent the insertion slot. The side of the blade which faces the plunger then acts to restrain the flap against the outwardly directed force exerted on a portion of the wall which is being displaced in order to set the lock.

The objects, features and advantages of this invention will appear more fully from the detailed description which follows accompanied by drawings showing, for the purpose of illustration, representative embodiments of the invention, it being understood that, in view of the widely varying configurations of the lock elements, no specific embodiment can properly be termed the preferred embodiment. The invention also resides in certain new and original features of construction and combination of ele* ments hereinafter set forth and claimed.

Although the characteristic features of this invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself, its objects and advantages, and the manner in which it may be carried out may be better understood from the following description taken in connection with the accompanying drawings forming a part of the disclosure in which:

FIG. 1 is a perspective view of a representative form of box blank resting on the mouth of a forming die:

FIG. 2 is a perspective view of an initial phase of the box forming operation by a plunger driving the blank into the die;

FIGS. 3, 4 and 5 are perspective illustrations of successive operations performed on the blank, the views being from the underside of the die;

FIGS. 6 and 7 are downward views into the die to show the relative location of critical plunger and die elements;

FIG. 8 is a perspective view of a partially modified plunger above a blank embodying corner lock elements of different configuration;

FIG. 9 is a perspective view of the plunger of FIG. 8 with the box blank of FIG. 8 folded about it, a portion of the blank being torn out along a hatched tear line to 3 show the back-up function performed by the plunger on certain portions of the blank;

FIG. is a perspective view of the blank of FIG. 8 passing through the die at the moment of the setting of the lock; and

FIG. 11 is a perspective view of a blank similar to that of FIG. 8 on which backing-up operations are being performed by a blade on the die.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to be generic in their application. Corresponding reference characters refer to corresponding parts in the several figures of the drawrngs.

The drawings accompanying and forming a part of this specification disclose certain specific details of Construction for the purpose of explanation of broader aspects of the invention, but it should be understood that structural details may be modified in various respects without departure from the principles of the invention and that the invention may be incorporated in other structural forms than shown.

The box blank A in FIG. 1 comprises a bottom panel 11 to which side panels 12, 13 are articulated along side fold lines 14 and 15. Corner flaps 16, 17, 18 and 19 are articulated to the side panels along corner fold lines 20, 21, 22 and 23.

End panels 24, 25 are articulated to the bottom panel along end fold lines 26 and 27, respetcively.

Means for interlocking the corner flaps with the end panels comprise curved or angled engagement slots 28, 29, 30 and 31 in the corner flaps and further slots in the end panels.

The illustrated blank is an experimental or test blank in which interlocks of different configuration are provided at the four corners in order to test four different locks simultaneously under substantially identical conditions.

Two slots are formed in the end panel 24 at the corner nearest the observer. Slot 32 is an insertion slot and slot 33 an engagement slot which is to be brought into engagement with the engagement slot 28 in corner fiap 16.

The wall slots for the other three corners are threearmed star cuts 34, 35, 36 which, as will later be seen, provide three essential elements, viz, an insertion slot, an engagement slot and a lug or tab in the end wall which becomes a safety catch for the purpose of maintaining portions of the engagement slots in edge-to-edge engagement. Usually two arms of the star out form the insertion slot and the third arm becomes an engagement slot,

either by itself or in conjunction with one or the other of the remaining star cuts.

The blank A is deposited by a suitable transport or feeder device over the mouth of a forming die between locating pins 37 which insure precise location of the blank with respect to the die 38, the major elements of which are best seen in FIGS. 6 and 7.

The die aperture is of substantially rectangular outline as is the plunger 39. The plunger has a bottom 40 (FIG. 8), sides 41 and ends 42 and comprises a central stem 43 leading to the reciprocating arm of a machine which moves the plunger back and forth through the die in a manner known per se.

The die comprises side folders 44 for folding certain blank panels against the side 41 of the plunger and, opposite the plunger end 42, a corner slide 45 for folding the corner flap 16 of the blank over the end panel 24 while the side panel 12 of the blank is being erected.

The plunger comprises further at its end a protruding element 46 adapted to engage the end panel 24 adajcent an insertion slot in the latter to open the slot for entry therein of the corner flap. A back-up element limits deflection of the blank under action of the protruding element 46 away from the plunger. The back-up element has the form of substantially upright folding bars 47 comprising slanted upper ends 48 which function in the folding of the end panels against the plunger end 42. The protruding element 46 lies between the corner slide 45 and the back-up element 47.

The plunger-and-die construction as described to this point is known and is disclosed, for example, in the above mentioned Pagendarm patent in which also the side folders are shown to be of pivoted spring-urged construction.

The folding and corner flap inserting action of the plunger-and-die device will be explained further below by reference to FIGS. 2, 3 and 4. The engagement and setting of the corner lock of the folded blank is accomplished by a mechanism which will now be described.

There is provided on the plunger a movable finger or pin 49 in a position to engage the end wall adjacent the lock tab and force the tab outwardly in a direction towards the die. This finger is shown in FIG. 7 in projected, and in FIGS. 6 and 8 in retracted, position. The plunger end 42 is preferably cut out about the pin or finger 49, as shown at 50, to provide for adjustment up or down, right or left of the finger to fit blanks in which the lock tab or tip is found in different positions.

The adjusta'bility of the fingers 49 and the provision of exchangeable bottom plates 51 (FIG. 8) makes the plunger universal for boxes of different specific lock configuration, but of the same bottom dimensions, major changes in box height being compensated by bottom plates 51 of different thickness.

As can best be seen in FIG. 7, the finger 49 is in a position opposite the lateral edge 52 of the corner slide 45.

An actuating mechanism is provided for the finger which is operated in timed relationship with respect to the plunger travel through the die to move the finger into a position of maximum projection beyond the plunger end 42 before the top edge 53 of the side wall of the box passes beyond, and is disengaged from, the side folders 44.

This condition is illustrated in FIGS. 3 and 11 showing approximately the moment of maximum projection of the fingers while the side walls 12 and 13', respectively, are still being engaged by the side folder 44. In addition, the actuating mechanism is so timed as to withdraw the fingers fully from the box before the plunger reaches the end of its travel through the die.

Referring to FIG. 5, the plunger 39 reaches its end position when the upper edge 53 of the box moves just below the ends of the folding bars 47, which then catch on the upper box edge and prevent the box from following the plunger during its upward stroke.

The actuating mechanism is similarly constructed as the mechanism disclosed in the above mentioned patent, but operates differently. It comprises basically a roller 54 on the plunger which engages a suitably shaped cam 55 on the die.

Referring to FIGS. 6 and 8, the plunger carries a pair of bearing blocks 56 through which a shaft 57 extends. A pair of downwardly extending levers 58 are clamped to the shaft near the ends of the latter. The fingers or pins 49 are secured to the lower ends of the levers to extend in a direction substantially parallel to the plunger bottom.

To the central portion of the shaft a pair of hell crank shaped levers 59 are secured in a position to carry the roller 54 between them. A yoke 60 extends between the horizontal arms of the levers 59 and bears down on a helical spring 61 which tends to maintain the respective finger, shaft and lever assembly in a position in which the fingers are fully retracted, as they are shown in FIG. 8. A bolt 62 extending through the yoke 60 limits the upward movement of the latter.

In the position shown in FIG. 7 the roller 54 has engaged the cam track 55 causing the finger 49 to become projected. In FIGS. 6 and 7 no blank is present, as a blank would have obscured relevant portions of the mechanism.

Returning now to FIG. 1 and considering the operation required to form the blank A into box shape:

The plunger seats on the bottom panel 11 of the blank and forces the blank into the die.

At the beginning of the folding operation the blank rests on the curved top portion 48 of the elements 47 which initially act as folding elements for the end panel 24 and fold it upright against the end of the plunger (FIG. 2). Shortly thereafter the side panel 12 is engaged by the side folders 44 and is being folded towards the plunger side 41. Simultaneously the corner slide 45 folds the corner flap 1'6 relatively to the side panel 12 and folds the flap over the end panel in a position in which the edge of the flap 16 is still some distance away from the insertion slot which is being opened up by the element 46 protruding from the plunger wall (FIG. 6) and bearing against the end panel 24 from the plunger side. This causes the insertion slot 32 to open at the near corner. At the far corner the slot 35 is open and the corner flap 18 can be seen entering it.

As the blank moves more deeply into the die the corner flaps 16, 18 reach their position of full insertion at the moment the respective side panels 12 and 13 are upright with respect to the bottom panel 11.

When the position shown in FIG. 4 is reached, the fingers or pins 49' are in their position of maximum projection and cause tips or points 63, 64 of tabs formed in the panel 24 to be snapped through the engagement slot 28 and the V-shaped engagement slot portion of the star cut 35.

It is seen from FIG. 4 that the lugs or tips 63, 64 extend beyond the confines of the respective engagement slot and become safety catches once they are snapped through the engagement slot. The catches are then effective to maintain edge portions of the engagement slots 28, 33 and 30', 35 in interlocking engagement. The corner structures of the box are thus locked in place.

In order to insure positive displacement of the tips through the slots 33, 35, bulging out of the end wall 24- rnust be, and is, prevented adjacent the respective slots by back-up elements. In FIG. 4 a single back-up roller 65 is shown for the left corner and a pair of rollers 66, 67 for the right corner. The rollers are on shafts 68, 69 secured to brackets 70, 71 on the centrally disposed back-up bar 47.

At the moment the tips 63, 64 are being snapped through the respective slots 33, 35, the side panels 12 and 13 are still in contact with the side folders 44, but move beyond them shortly thereafter.

In the position shown in FIG. the top edge of the box has cleared the side folders 44 and is about to become engaged by the lower ends of the bars 47 which then strip off the box when the plunger commences its upward return stroke. Also the pins or fingers 49 are fully retracted as the actuating roller 54 has moved beyond the end of the cam 55 (compare FIG. 4 in this respect).

FIG. 8 shows a blank B incorporating slots of a configuration which require no back-up elements on the die for setting the lock, i.e., for forcing the safety catch tips through the respective engagement slots. For the sake of simplicity reference numerals are applied to the blank B which differ by 100 from the reference numerals used for blank A. The slot configurations 130, 135 are alike at all four corners. Only the assembly of the near corner of FIG. 8 will be described and only the near corner of the plunger was modified for this purpose.

A glance at FIG. will show that the back-up rollers were removed from the brackets 70.

It is seen that the protruding pin 46 was replaced by a blade 146 slightly slanted with respect to the surface of the plunger end 42 and extending toward the observer. The blade 146 has a squared-off end 147 which bears against the end panel 124 adjacent the star cut 135. It causes the insertion slot to open for entry of the corner flap 118 which then passes under the blade. This is seen in FIG. 9 in which a portion of blank B was torn out in order to expose the blade.

When the pin or finger 49 is then projected to snap the tip 164 through the engagement slot the blade 146 backs up the corner flap 118 closely adjacent the slot.

In FIG. 9 the die is removed and the left box corner is shown disassembled by withdrawal of its flap 118 to illustrate details of the lock.

FIG. 10 shows the blank B passing through the die at the moment of the setting of the lock. The tip 164 is clearly visible at the near corner.

FIG. 11 illustrates still another lock configuration in which an upwardly directed tip or point 264 forms the safety catch and in which the back-up element on the die is a blade 266.

What is claimed is:

1. In a device for erecting and interlocking the corner of a folding box blank of the type comprising a main panel, side panels, end panels and a lock flap articulated to the end of a certain side panel along a corner fold line, said lock flap being foldable over, and insertable through, an insertion slot in the end panel with which said certain side panel forms a box corner, there being an engagement slot in said lock flap which in corner forming position partially coincides with, and partially deviates from, said insertion slot, the deviating portion of the slots defining a lock tab on said end panel to be snapped past an edge of the engagement slot,

the device comprising a plunger and a die through which the plunger is movable, the plunger comprising a bottom, sides and ends, the die comprising a side folder for folding said certain side panel against the plunger side and, opposite a plunger end, a corner slide for folding the lock flap over the end panel while the side panel is being erected, the plunger comprising further at its end a protruding element adapted to engage the end panel adjacent the insertion slot to open the slot for entry therein of the lock flap, the device further comprising a backup element for limiting deflection of the blank away from the plunger end, the protruding element being located between said corner slide and said back-up element,

the improvement which comprises a movable finger mounted on said plunger in a position to engage said lock tab and force it outwardly towards the die; and actuating means for said finger so timed with respect to the plunger travel through the die as to reach a position of maximum projection beyond the plunger end before the top edge of the side wall passes beyond, and is disengaged from, said side folder and to move into retracted position by the time the plunger reaches the end of the stroke through the die.

2. A device according to claim 1 in which the movable finger is substantially opposite the lateral edge of the corner slide and is projected after pass-ing the slide.

3. A device according to claim 1 in which a back-up element is mounted on the die to engage the end panel adjacent the insertion slot to urge the end panel towards the plunger at a zone below the corner slide.

4. A device according to claim 3 in which the backup element is a roller.

5. A device according to claim 1 in which a pair of back-up elements is mounted on the die at a level below the corner slide in a position to engage the end panels and the lock flap, respectively, adjacent the path of the finger and to urge said end panel and lock flap towards the plunger, the pair of elements being disposed to straddle the insertion slot.

6. A device according to claim 1 in which the pro- References Cited trud-ing element comprises a blade-shaped end portion directed towards the adjacent plunger corner, the length UNITED STATES PATENTS of the blade being sufficient to permit the lockflap to 2,604,022 7/1952 Bellato 93-51 pass under the blade into fully inserted position through 5 2,873,655 2/1959 Johnson et a1. 1 said insertion slot, the end of the blade flaring out from 3,37 ,797 4/1968 Scace 9351 the plunger end and terminating adjacent the insertion slot. BERNARD STICKNEY, Primary Examiner 

